There is no difference between trim models in regards to the strut casings, the difference lies in whether the vehicle had power steering or not (though if STs had no PS, that wouldn't be the case). Up here I belive we just got GTs and GTSs (I recall encountering one non PS celica here once, but only one), and they all seem to have power steering and they all have the right struts. Basically, if the car came with PS, it has the short steering arms and it has the correct strut casings, but I'm pretty sure even the non PS strut casings will have the same axel angle. The length of the steering arm has no effect on what the ideal axel angle would be.
This thread is really old and I'm sure full of some outdated and contradictory information by now, so its time for a little refreshing (I'd like to replace the whole thing at some point actually). It should be mentioned here now that the primary reason for doing this mod can now be attained easier by ordering Techno Toy Tunning's short steering arms made specifically for the mk2...
https://technotoytuning.com/toyota/ma60/steering-knuckles-ma60-supra
These arms retain the stock ball joint offset as the stock mk2 arms, so you don't need the celica strut casings.
HOWEVER, there is still a very significant advantage to my original mod. Since the PS ra6x Celica steering arms relocate the strut further inboard, and due to the corrections you have to make to retain proper camber (celica strut casings and camber brackets, more on that in a sec), you end up moving the entire strut inboard top and bottom and create approx an extra half inch of front wheel spacing. This means you can run a rim with a lower offset (approx 10-13mm less) and fit a wider wheel. The caveat is even with the celica strut casings, you will still be at slightly less negative camber then stock. This mod requires camberplates, something I had not fully realized when I originally posted this thread. Its not off alot (I should still measure it to see just how much), but enough to hurt mid corner grip and affect outer tire wear. With camber plates though, you will have more then enough adjustment range. I run very aggressive camber settings at autox, almost maxed out on my cuscos, but I don't seem to need more negative camber (and track driving requires even less), my inner vs outer edge tire temps are quite good and my lateral grip seems to have peaked.
So what about scrub radius if you're running lower offset wheels you might ask. Well, more good news here. Generally going to a lower offset in the front screws up your scrub radius, as your tire's centerlne moves away from your "Dave point". Dave Coleman of Sport Compact Car fame took it upon himself to name the point on the ground that your tires rotate around. That point should always be as close to the centerline of your tire as possible. The offset your car came with from the factory was determined to position the tire dead center over your Dave point. Your Dave point is dictated by the location of the rotation points of the strut assembly (in a macpherson strut car anyways), so run a line from the top of the strut to the center base of the ball joint and extend that line to the ground and thats your Dave point. With my celica strut mod, the ball joint stays in place, but the top of the strut (and the rest of it) move inboard, which effectively projects the Dave point outwards. Thus, you actually should run a lower offset to maintain the factory scrub radius. This works for me as I like my old school, low offset jdm wheels, but for those who have already settled on their +10ish offset wheels, its another thing to consider before going this route (and yes spacers can help with this). FYI, I run 15x8 -12 upfront right now and have plenty of flare to tire clearance (actually more then I'd like) with 225 tires and slightly more agressive camber then stock.
